feat: add Docker deployment (backend:18889, frontend:18888)

- Dockerfile.backend: Python 3.11 + FastAPI + uvicorn
- Dockerfile.frontend: Node 20 build + Nginx serve
- docker-compose.yml: orchestration with data volume mount
- nginx.conf: API/WebSocket proxy to backend
- web/backend/requirements.txt: Python dependencies
- .dockerignore: exclude venv/node_modules/data from build

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Dockerfile.backend

@@ -0,0 +1,28 @@
+FROM python:3.11-slim
+
+WORKDIR /app
+
+# Install system dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Python dependencies
+COPY web/backend/requirements.txt .
+RUN pip install --no-cache-dir -r requirements.txt
+
+# Copy project files
+COPY app/ ./app/
+COPY config/ ./config/
+COPY config.ini ./
+COPY templates/ ./templates/
+COPY web/ ./web/
+
+# Create data directories
+RUN mkdir -p data/input data/output data/result data/temp
+
+# Expose port
+EXPOSE 18889
+
+# Run
+CMD ["python", "-m", "uvicorn", "web.backend.main:app", "--host", "0.0.0.0", "--port", "18889"]